1. Field of the Invention
The present invention relates in general to a clutch drum used in an automatic transmission and a method of producing same, and more particularly to a clutch drum having thereon press-formed splines and a method of producing same.
2. Description of the Prior Art
In the field of automatic transmissions using therein wet type multi plate clutches, there is known a type which comprises a clutch drum of which inner and outer cylindrical surfaces are both formed with splines or axially extending grooves. Upon assembly, the inside splines of the drum are mated with the external teeth of inner clutch plates disposed in the drum, while, the outside splines of the drum are mated with the internal teeth of outer clutch plates disposed about the drum. The outer clutch plates secure the clutch drum to a suitable fixed member when fixed. Usually, the outside and inside splines of the clutch drum of the type mentioned above are formed by employing a press-forming technique. However, due to their inherencies, some of the conventional press-forming techniques fail to provide the splines with adequate engaging surfaces which are to be actually engaged with the teeth of the clutch plates. This will be described in detail hereinafter for clarification of the invention.